--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests.py	Mon Dec 08 20:18:03 2025 +0000
@@ -0,0 +1,42 @@
+import pytest
+
+from bio2srr import *
+
+
+def test_element_tree_xpath():
+    from xml.etree import ElementTree as xml
+    root = xml.fromstring(biosample_example)
+    assert root.find(".//Id[@db='BioSample']") is not None
+
+def test_flatten_biosample_xml():
+    d = flatten_biosample_xml(biosample_example)
+    assert d['biosample_accession'] == 'SAMN17131268'
+    assert d['organism'] == 'Campylobacter jejuni'
+    assert d['isolate'] == 'CFSAN091032'
+
+def test_flatten_runs():
+    d = list(flatten_runs(runs_example))
+    assert len(d) == 2
+
+def test_header_sort_override_consistency():
+    import random
+    L = ["C", "B", "A", "taxid", "bioproject"]
+    L.sort(key=hso)
+    # assert L[0] == "bioproject"
+    A = L.copy()
+    assert A == L
+    R = []
+    for _ in range(100):
+        random.shuffle(A)
+        A.sort(key=hso)
+        R.append(A == L)
+    assert all(R)
+
+def test_hso_override():
+    assert header_sort_override("bioproject", "taxid") < 0
+    assert header_sort_override("taxid", "bioproject") > 0
+    assert header_sort_override("taxid", "taxid") == 0
+
+def test_hso_regular():
+    assert header_sort_override("A", "B") < 0
+    assert header_sort_override("B", "A") > 0
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